Tractors, in particular backhoe loaders are often employed in many aspects of construction and excavation including loading, lifting, craning, digging, dozing, spreading and grading. Seldom will it be found that a single bucket can be employed for all of these activities. Therefore, various bucket designs are used depending upon the operation being performed. Hence, it is necessary to provide adequate means for detachably connecting a bucket to a backhoe loader so that any bucket may be readily interchanged with another.
A bucket is commonly detachably interlocked to the dipper stick of a backhoe loader by equipment locking pins. Tractor equipment pins generally comprise a hardened metal pin having an enlarged head with a retaining ring pivotally mounted thereto. The retaining rings of most tractor equipment pins are easily swung into and out of a retaining position upon encountering debris or vibrations thereby leaving the pin free to be shaken from its mounted position.
Improvements for connecting excavating implements such as a bucket to a machine such as a tractor have been made in the prior art. U.S. Pat. No. 2,856,806 which issued to Gibbons on Oct. 21, 1958, entitled "COUPLING PIN WITH PIVOTABLE SECURING RING" discloses a coupling pin with a spring loaded retractable bolt retained within the pin and a pivoting pull ring. To lock the pin, the bolt is first retracted within the pin. Thereafter, the pivoting pull ring is swung downwardly to a position inboard of the retractable bolt. At such a time the bolt is released so as to return to its normal extended position whereupon the pull ring is held adjacent to the bolt shaft. The pull ring however, is left free to swing free behind the bolt, and therefore it is susceptible to becoming snagged or elongated in such a manner as to damage or accidentally dislodge the pin.
U.S. Pat. No. 4,840,528 which issued to Doom on June 20, 1989 entitled "LOCKING HITCH PIN ASSEMBLY" discloses a hitch pin assembly for locking equipment to a tractor. The hitch pin comprises a locking pin having a pivoting pull ring serving as the locking mechanism. A retractable spring loaded rod having a keeper notch is disposed in the pin. An access slot is provided in alignment with the notch to allow receipt of the pull ring. To lock the pin the pull ring is swung downwardly so as to enter the access slot. Thereafter, the spring loaded rod is retracted into the pin so as to allow the keeper notch to engage the pull ring. At such a time the retractable rod is released and allowed to return to its normally extended position whereupon the hitch pin is locked.
Another prior art locking pin is disclosed in a German patent application which was Laid-open for public inspection, Offenlegugsschrift 28 19 624, on May 5, 1978. The latter German patent application discloses a locking pin which includes a plug shaft having a plug head through which extends an aperture. A spring washer formed from a spring steel wire is pivotally mounted in the aperture in the plughead. The spring washer is formed with a resilient jaw shaped clamp. Upon locking the pin the spring washer is pivoted such that the resilient clamp makes contact with the lower end of the plug shaft and, thereupon the clamp deflects so as to seize the plug shaft. At such a time the prior art pin is locked. In order to open the pin, the spring washer must be pulled so as to cause the resilient clamp to deflect and disengage the plug shaft. Repeated opening and closing operations will eventually cause the spring steel wire to deform and eventually fail, whereby the pin will have to be discarded.
It is therefore an object of the subject invention to provide a locking pin for connecting a bucket to backhoe loader having a rigid retaining ring that will not deform.
It is a further object of the subject invention to provide a locking pin for connecting a bucket to a backhoe loader that is inexpensive to manufacture.